Maple sap is a great source of natural sugar and certainly qualifies as home winemaking material. What is less certain, as you have found out, is how much of those subtle maple aromas and flavors will stick around in a finished wine. I’m glad you’re experimenting with adding acid. Like you’ve discovered, maple syrup just doesn’t have enough natural acid on its own to create a
balanced finished product. Acid blends will usually have a combination of malic and tartaric acids, which better mimic a grape’s natural acid profile and will help contribute to a better eventual mouthfeel and refreshing “zing”.
Lemon rinds, especially, (as it seems you’ve discovered) can contribute what is perhaps unwanted lemony aromas and flavors. Don’t forget that what makes a lemon “lemony” is all about that tiny, thin layer of yellow-colored zest on the very outside of the fruit. It’s after all why a martini “with a twist” can taste so citrusy with just a brush of lemon peel. The pith, or the white part underneath the yellow peel, is chock full of bitter and astringent compounds, which you most likely don’t want to get into your finished wine. It’s undoubtedly contributing to those “lemonade” flavors that you describe not wanting.
To improve body and overall mouthfeel profile I suggest replacing about 1⁄2 to 1⁄3 of your sugar source (maple syrup) with a neutral white grape juice concentrate like Thompson Seedless or even Chardonnay. This will provide enhanced natural acid and body components and will also provide better yeast nutrition. If you’re looking to get more natural maple flavor into this project, might I suggest shopping for a little bottle of natural maple flavor online or at your local natural foods store? Add it when your wine is done fermenting (make sure it doesn’t contain any sugar, most do not) and in very small initial doses as some brands are quite strong. This sounds like a great brunch wine with pancakes!
